EVIDENCE FOR HOST AS THE MAJOR CONTRIBUTOR TO LIPID IN THE INTRAVACUOLAR NETWORK OF TOXOPLASMA-INFECTED CELLS

Eukaryot Cell. 2011 Jun 17. [Epub ahead of print]

EVIDENCE FOR HOST AS THE MAJOR CONTRIBUTOR TO LIPID IN THE INTRAVACUOLAR NETWORK OF TOXOPLASMA-INFECTED CELLS

Caffaro CE, Boothroyd JC.
SourceDepartment of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA.

Abstract
The intracellular parasite, Toxoplasma gondii, develops inside a parasitophorous vacuole (PV) that derives from the host cell plasma membrane during invasion. Previous electron micrograph images have shown that the membrane of this vacuole undergoes an extraordinary remodeling with an extensive network of thin tubules and vesicles, the intravacuolar network (IVN), which fills the lumen of the PV. While dense granule proteins, secreted during and after invasion, are the main factors for the organization and tubulation of the network, little is known about the source of lipids used for this remodeling. By selectively labeling host cell or parasite membranes, we uncover evidence that strongly supports the host cell as the primary, if not exclusive, source of lipid for the parasite IVN remodeling. Fluorescence Recovery After Photobleaching (FRAP) microscopy experiments reveal that lipids are surprisingly dynamic within the parasitophorous vacuole and are continuously exchanged or replenished by the host cell. The results presented here suggest a new model for development of the parasitophorous vacuole whereby the host provides a continuous stream of lipids to support the growth and maturation of the PVM and IVN.

PMID:21685319[PubMed - as supplied by publisher]